Chitosan systems

M. Zhang, A. Smith, and W. Gorski, Carbon nanotube-chitosan system for electrochemical sensing based on dehydrogenase enzymes. Anal. Chem. 76, 5045-5050 (2004). 

Rinaudo M, Auzely R et al (2005) Specific interactions in modified chitosan systems. Biomacromolecules 6 2396-2407... 

Most of the early studies on chitosan system processing dealt with the purification of chitosan itself to remove impurities such as proteins, pyrogens, toxic metals, and low molecular weight polysaccharides. Chitosan purification was pursued primarily to allow its use in parenteral pharmaceutical products and/or implantable biomedical devices. Parallel to chitosan purification, a great deal of effort was directed toward chitosan processing into ... 

C.T. Laurencin, T. Jiang, S.G. Kumbar, L.S. Nair, Biologically active chitosan systems for tissue engineering and regenerative medicine, Curr. Top. Med. Chem. 8 (2008) 354-364. 

Figure 21.5 Schematic comparison for delivery processes of (a) intracellular-responsive Schiff base-linked imidazole chitosan system and (b) traditional cationic polymer-based gene delivery stem.

Section II is devoted exclusively to polysaccharide systems, but includes a fairly broad variety of polymers and applications. Kennedy et al. describe some industrially important polysaccharides, while Morris covers various bacterial-derived polysaccharides used in the food and agricultural industries. Carraher et al. describe some tin modified dextrans in the third Chapter of this Section. Some acidic, heparin-like, polysaccharides are described in the following Chapter (Linhardt, et al.) then Kobayashi reveals some cellulose derivatives which form liposomes and membranes. The final three papers of this Section deal with chitin and chitosan systems. Alkaline chitosan gels are presented by Hirano et al. Kikuchi and Kubota then describe some polyelectrolytes derived from chitosan derivatives. Finally, Seo and lijima consider the sorption behavior of chitosan gels. 

De la Riva, B., Sanchez, E., Hernandez, A., Reyes, R., Tamimi, R, Lopez-Cabarcos, E., Delgado, A., and Evora, C. 2010. Local controlled release of VEGF and PDGF from a combined brushite-chitosan system enhances bone regeneration. Journal of Controlled Release 143 45-52. 

It has also long been acknowledged that the presence of a small amount of salt leads to a more uniform distribution of the short chain components among the polyelectrolyte with the longer chains, and thus thermodynamic equilibrium [23], More recently it has also been demonstrated that temperature annealing can lead to more organized liquid crystalline structures of DNA—lipid systems [55] and single-molecule structures of xanthan—chitosan systems [56] (see below). 

In vivo studies have shown that 80% of the PDGF was released from the brushite-chitosan composite scaffold within 2 weeks, while only 70% of VEGF was delivered in 3 weeks. Both growth factors that were released from the con-stmcts remained near the implantation site (5 cm) with negligible systemic exposure. The results indicate that the brushite-chitosan system can control the release rate and localization of both growth factors in a bone defect. PDGFA EGF-loaded brushite-chitosan scaffolds greatly promoted bone formation [211]. 

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